Air conditioner indoor unit

Abstract

The utility model provides a kind of air conditioner indoor unit, it includes: fresh air fan, it includes: volute, fan cavity is defined in it, volute is equipped with and volute air inlet and volute air outlet of fan cavity intercommunication on volute;Centrifugal impeller, is located in fan cavity;Air inlet cover, connect with volute and jointly define air inlet cavity, air inlet cavity with fan cavity are communicated by volute air inlet;Air inlet pipe, one end is connected with air inlet cover, the other end forms fresh air air inlet;Flow guide structure, is located on the side wall of air inlet cover away from centrifugal impeller, flow guide structure includes two flow guide pieces sequentially arranged along the axis direction of fresh air air inlet, two flow guide pieces form flow guide passage, flow guide passage is from upstream to downstream first contraction then expansion tendency.The utility model in, by the position of fresh air air inlet is reasonably set to give airflow pre-rotation, and two-stage flow guide structure is used to reduce the circumferential momentum loss of airflow in wind cavity, increase the axial velocity of airflow, improve fan doing function ability.

Description

Technical Field

[0001] This utility model belongs to the field of air conditioning technology, and in particular relates to an indoor unit of an air conditioner. Background Technology

[0002] As people's demands for indoor air quality increase, air conditioning indoor units with fresh air functions are gradually becoming the mainstream in the market. A typical fresh air conditioning indoor unit includes a casing, a fresh air fan housed within the casing, and an air intake chamber connecting to the outside. Fresh outdoor air is introduced through the air intake duct, passes through the air intake chamber and filter assembly, and is then delivered indoors by the fresh air fan, achieving indoor-outdoor air exchange. The air intake chamber is formed by the connection between the air intake shroud and the volute casing; the structural design of the air intake shroud directly affects the airflow, efficiency, and noise performance of the fresh air system.

[0003] In existing technologies, various fresh air module structures have been proposed to optimize airflow and reduce wind resistance within the air inlet cavity. For example, rounding the corners of the air inlet cavity or installing a flow guide device within it. Rounding the corners reduces airflow vortices and kinetic energy loss caused by dead zones. The flow guide device uses a first and second guide vane to divide the direct airflow into two pre-swirling airflows with the same or opposite directions, preventing the airflow from blowing directly onto the sidewalls of the air inlet cavity, reducing diffusion and impact losses, and thus increasing the fresh air volume. The guide vane structure can be a herringbone shape, bent in the same direction, etc., to adapt to fans with different rotation directions.

[0004] The aforementioned airflow guiding device design fails to adequately consider the relationship between the fan impeller's rotation direction and the inlet position, resulting in significant circumferential momentum loss and low overall kinetic energy utilization when the airflow enters the fresh air fan. Furthermore, existing airflow guiding devices are mostly single guide vanes or simple bifurcated structures, merely guiding the airflow quickly to the volute inlet of the fresh air fan without considering the rapid change in airflow direction from radial to axial. This can easily lead to increased airflow instability and uneven pressure distribution, negatively impacting fan efficiency and noise levels. Additionally, the rounded corners of the inlet cavity offer limited improvement because they do not alter the main motion pattern. Utility Model Content

[0005] This utility model aims to at least partially solve one of the technical problems in related technologies. Therefore, This utility model provides an indoor unit for an air conditioner, which includes: A housing having an internally defined receiving space, the housing including a fresh air outlet; A fresh air fan, installed in the accommodating space, is used to introduce fresh outdoor air. The fresh air fan includes: A volute, which defines a fan cavity inside, is provided with a volute air inlet and a volute air outlet communicating with the fan cavity, and the volute air outlet is connected to the fresh air outlet. A centrifugal impeller is disposed inside the fan cavity, and the centrifugal impeller rotates in a first direction; An air inlet shroud, connected to the volute, together defines an air inlet cavity, which is connected to the fan cavity through the air inlet of the volute. An air inlet duct, one end of which is connected to the air inlet hood, and the other end of which forms a fresh air inlet communicating with the air inlet cavity; A flow guiding structure is provided on the side wall of the air inlet shroud away from the centrifugal impeller to guide the airflow entering the fresh air inlet to form a pre-swirling airflow, the rotation direction of the pre-swirling airflow being opposite to the first direction; The airflow guiding structure includes two airflow guiding vanes arranged sequentially along the axial direction of the fresh air inlet, and an airflow guiding channel is formed between the two airflow guiding vanes. The airflow guiding channel has a tendency to first contract and then expand from upstream to downstream. The guide vane closer to the fresh air inlet is defined as the first guide vane, and the other guide vane is defined as the second guide vane. The tangent at the upstream end of the profile of the first guide vane is parallel to the central axis of the air inlet duct.

[0006] The above technical solution has the following advantages or beneficial effects: the airflow entering through the fresh air inlet passes through two stages of guide vanes, which effectively reduces the circumferential momentum loss of the airflow, increases the axial velocity, and reduces the flow resistance and kinetic energy loss of the air inlet cavity, thereby improving the fan's air volume and efficiency, and effectively solving the problems of high air inlet cavity resistance and excessive airflow tangential velocity leading to kinetic energy loss in the existing technology.

[0007] According to an embodiment of this disclosure, the first guide vane is arc-shaped, the diameter of the fresh air inlet is d, and the arc radius r1 of the first guide vane satisfies: r1≥1.5d, r1≤2d.

[0008] The above technical solution has the following advantages or beneficial effects: If the arc radius r1 is less than 1.5d, the curvature will be too large, causing a sharp change in airflow direction and easily resulting in significant impact loss and flow separation. If the arc radius r1 is greater than 2d, the curvature will be too small, and the circumferential velocity attenuation of the airflow will not be significant, which is not conducive to increasing the axial velocity of the airflow, resulting in severe airflow loss and hindering the achievement of drag reduction. The first guide vane adopts an arc-shaped design, with an arc radius r1 within the range of 1.5d to 2d, which optimizes airflow direction, reduces local eddies and separation, and allows the airflow to smoothly transition to the second-stage guide vane, resulting in a significant drag reduction effect.

[0009] According to an embodiment of this disclosure, the central angle a1 corresponding to the first guide vane satisfies: a1≥55°, a1≤70°.

[0010] The above technical solution has the following advantages or beneficial effects: A central angle a1 greater than 70° will cause excessive airflow deflection, increasing friction loss and reducing fan efficiency. A central angle a1 less than 55° will result in insufficient deflection, preventing effective pre-swirl of the airflow and reducing drag reduction. By setting the central angle a1 within the range of 55° to 70°, effective pre-swirl and deflection of the airflow are ensured, reducing energy loss.

[0011] According to an embodiment of this disclosure, the distance t between the first guide vane and the end of the air inlet pipe furthest from the fresh air inlet satisfies: t≥0.25d, t≤0.35d.

[0012] The above technical solution has the following advantages or beneficial effects: When the spacing t > 0.35d, the airflow may diffuse prematurely, leading to energy loss and flow field instability. When the spacing t < 0.25d, the airflow is compressed, increasing impact loss and potentially inducing eddies. By setting the spacing t within the range of 0.25d to 0.35d, airflow impact loss is reduced, ensuring smooth airflow entry into the guide structure and avoiding energy loss problems caused by compression or diffusion when the airflow enters the guide structure.

[0013] According to an embodiment of this disclosure, the second guide vane is arc-shaped, the diameter of the fresh air inlet is d, and the arc radius r2 of the second guide vane satisfies: r2≥1.5d, r2≤2d.

[0014] The above technical solution has the following advantages or beneficial effects: If the radius of the arc r2 > 2d, the airflow guidance is insufficient, the reduction in circumferential momentum is not significant, and the drag reduction effect is poor. If the radius of the arc r2 < 1.5d, the airflow turns too sharply, increasing flow separation and energy loss. By setting the radius of the arc r2 within the range of 1.5d to 2d, it forms an effective secondary flow guide in conjunction with the first guide vane, ensuring that the airflow smoothly turns on the second guide vane, further reducing circumferential momentum loss, increasing the axial velocity of the airflow, and improving the performance of the fresh air fan.

[0015] According to an embodiment of this disclosure, the central angle a2 corresponding to the second guide vane satisfies: a2≥90°, a2≤120°.

[0016] The above technical solution has the following advantages or beneficial effects: If the central angle α2 exceeds 120°, it may cause excessive airflow deflection, increasing friction loss and drag. If the central angle α2 < 90°, the curvature of the second guide vane is small, resulting in weak airflow guidance and an inability to form an ideal reverse pre-swirling flow field. The circumferential velocity of the airflow remains high, limiting the increase in axial velocity. By setting the central angle α2 of the second guide vane within the range of 90°~120°, sufficient airflow deflection is ensured, increasing axial velocity, reducing circumferential momentum, and improving the work capacity of the fresh air fan.

[0017] According to an embodiment of this disclosure, the air inlet shroud has a second sidewall adjacent to the fresh air inlet and a third sidewall opposite to the fresh air inlet, and the diameter of the fresh air inlet is d; The distance L1 between the upstream end of the second guide vane and the second sidewall satisfies: L1≥0.5d, L1≤0.55d; and / or, the distance L2 between the upstream end of the second guide vane and the third sidewall satisfies: L2≥0.97d, L1≤1.1d.

[0018] The above technical solution has the following advantages or beneficial effects: If L1 < 0.5d or L2 < 0.97d, the second guide vane is too close to the wall of the air inlet shroud, causing flow blockage or dead zones and increasing resistance. If L1 > 0.55d or L2 > 1.1d, the second guide vane may be too close to the center of the air inlet cavity, resulting in insufficient airflow guidance and insignificant reduction in circumferential momentum. When distances L1 and L2 are within the given range, the position of the second guide vane in the air inlet cavity is optimized, avoiding interference with the wall of the air inlet shroud, guiding the airflow to a uniform distribution, reducing the pressure gradient within the air cavity, and improving the uniformity of the flow field.

[0019] According to an embodiment of this disclosure, the minimum distance Lmin between the first guide vane and the second guide vane satisfies: Lmin≥1d, Lmin≤1.2d.

[0020] The above technical solution has the following advantages or beneficial effects: If the minimum distance Lmin > 1.2d, the guide channel is too loose, the airflow cannot be effectively accelerated, and the drag reduction effect is poor. If the minimum distance Lmin < 1d, the contraction point of the guide channel is too narrow, increasing flow resistance and impact loss. By setting the minimum distance Lmin within the range of 1d to 1.2d, controlling the cross-section of the guide channel to first contract and then expand optimizes the acceleration and deceleration of the airflow, reduces energy loss, and helps achieve the drag reduction objective.

[0021] According to an embodiment of this disclosure, one end of the guide vane is connected to the side wall of the air inlet shroud, and the other end extends towards the centrifugal impeller to form a free end. The two guide vanes have the same height h in the axial direction of the centrifugal impeller, where h satisfies: h≥0.45H, h≤0.52H; H is the thickness of the air inlet cavity in the axial direction of the centrifugal impeller.

[0022] The above technical solution has the following advantages or beneficial effects: If h > 0.52H, it is easy to interfere with the filter screen installed at the air inlet of the volute, affecting the installation and use of the filter screen. If h < 0.45H, it cannot effectively interfere with the main airflow, and the airflow reorganization is not obvious. By setting the height h of the guide vane within the range of 0.45H~0.52H, and making it related to the thickness of the air inlet cavity, it is ensured that the guide vane can effectively interfere with and guide the main airflow, reorganize the airflow, and at the same time avoid interference with the filter screen.

[0023] According to embodiments of this disclosure, the guide vanes are of uniform thickness, and the thickness m of the guide vanes satisfies: m≥2mm, m≤3mm; and / or, the central axis of the air inlet duct forms an acute angle with the ray pointing from the rotation center of the centrifugal impeller to the geometric center of the fresh air inlet, and the central axis is deflected in the opposite direction to the first direction relative to the ray.

[0024] The above technical solution has the following advantages or beneficial effects: If the thickness m > 3mm, the drag reduction effect will not be improved; instead, it will increase the weight and cost of the air inlet shroud. If the thickness m < 2mm, the strength of the guide vane is insufficient, and it may deform or be damaged after long-term use, affecting its service life. By setting the thickness m within the range of 2mm to 3mm, the structural strength and drag reduction effect of the guide vane are effectively balanced, solving the strength problem or ineffective weight increase problem caused by improper thickness of the guide vane. By setting the central axis of the fresh air inlet to form an acute angle with the ray pointing from the rotation center of the centrifugal impeller to the geometric center of the fresh air inlet, and the opening direction is opposite to the rotation direction of the impeller, the airflow will generate pre-swirl when entering the air inlet cavity. The pre-swirl direction is opposite to the rotation direction of the centrifugal impeller, which is beneficial to improving the work capacity of the fresh air fan, ultimately increasing the air volume and efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the appearance of the fresh air module according to one embodiment of the present disclosure; Figure 2 This is a schematic diagram of the appearance of the fresh air module from another perspective according to one embodiment of the present disclosure; Figure 3 This is a partial explosion diagram of the fresh air module according to one embodiment of this disclosure; Figure 4 This is an exploded view of the fresh air module according to one embodiment of the present disclosure; Figure 5 This is a structural schematic diagram of a fresh air fan according to one embodiment of the present disclosure; Figure 6 This is a cross-sectional view of a fresh air module according to one embodiment of this disclosure; Figure 7 This is a structural schematic diagram of the air inlet shroud according to one embodiment of the present disclosure; Figures 8-10 This is a side view of the air inlet shroud according to one embodiment of the present disclosure; Figure 11 This is a structural schematic diagram of the air inlet shroud from another perspective according to one embodiment of the present disclosure; Figure 12 This is a structural schematic diagram of a fresh air module according to one embodiment of the present disclosure; Figure 13 These are cloud maps comparing the circumferential velocity of the air inlet before and after the improvement. Figure 14 These are cloud maps comparing the axial velocity inside the air inlet before and after the improvement. Figure 15 It is a comparison cloud diagram of the static pressure of the air inlet cavity cross section before and after the improvement.

[0026] In the above figures: fresh air module 10; fresh air fan 1; volute 11; centrifugal impeller 12; volute air inlet 13; volute air outlet 14; fan cavity 15; air inlet hood 2; second side wall 22; third side wall 23; air inlet cavity 24; air inlet pipe 3; fresh air inlet 31; flow guiding structure 4; first flow guide vane 41; second flow guide vane 42; flow guiding channel 43; filter assembly 5; filter screen 51; filter screen support 52; through part 6; connecting structure 7. Detailed Implementation

[0027] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0028] In this utility model, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0029] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] An air conditioner's indoor unit is part of the air conditioner. It is installed indoors and used for heat exchange with the indoor environment. Additionally, an air conditioner includes an outdoor unit, which is typically located outdoors and used to transfer heat from the indoor environment to the outside.

[0033] The air conditioner indoor unit provided in this embodiment is a wall-mounted air conditioner indoor unit, which can have various implementation forms.

[0034] An indoor air conditioner unit may include a casing. The casing is installed on the indoor wall and forms the overall appearance of the indoor air conditioner unit. The casing is rectangular in shape, with its left and right ends being the two ends along its length.

[0035] The interior of the casing has a storage space. This space is used to house and secure the various components inside the air conditioner indoor unit, preventing collisions between external objects and these components, thereby improving the reliability of the air conditioner indoor unit during transportation or installation.

[0036] The housing may include an air conditioning inlet. The air conditioning inlet is connected to the housing space and serves as the inlet for external air to flow into the housing, allowing indoor air to enter the housing space through the air conditioning inlet.

[0037] The housing may include an air conditioning vent. The air conditioning vent is connected to the housing space and serves as an outlet for airflow within the housing, allowing airflow within the housing space to exit through the air conditioning vent.

[0038] In some embodiments of this application, the air conditioning inlet is located at the top of the housing. The air conditioning outlet may be located at the bottom front side of the housing.

[0039] The air conditioner vent is elongated and can extend along the length of the unit casing, improving the aesthetics of the indoor unit. In this embodiment, when the indoor unit is operating, air enters from the top and exits towards the bottom front, facilitating installation.

[0040] It should be noted that the directions described in the text are based on the direction the user faces when facing the indoor unit of the air conditioner. Specifically, the side of the indoor unit facing the user when in use is defined as the front side, and the opposite side is defined as the rear side. The left and right sides are distinguished by the direction the user faces when facing the indoor unit.

[0041] An indoor unit of an air conditioner may include an indoor heat exchanger. The indoor heat exchanger extends along the length of the unit casing and is located inside the casing to exchange heat with the airflow inside the casing.

[0042] An indoor unit of an air conditioner may include an indoor fan. The indoor fan is located within a housing space and is used to drive indoor air from outside the unit casing through the air conditioner inlet into the housing space inside the unit casing. The indoor fan drives the airflow within the housing space to flow from the air conditioner inlet toward the air conditioner outlet.

[0043] An air conditioner may include an outdoor heat exchanger and a compressor, which are installed in the outdoor unit of the air conditioner.

[0044] Air conditioners may include a throttling device. The throttling device is used to limit airflow. The throttling device can be provided in either the indoor or outdoor unit of the air conditioner.

[0045] Air conditioners execute a refrigeration cycle using a compressor, condenser, throttling device, and evaporator. The refrigeration cycle involves a series of processes including compression, condensation, expansion, and evaporation, supplying refrigerant to the conditioned and heat-exchanged air.

[0046] The compressor compresses the refrigerant gas at low temperature and low pressure and discharges it at high temperature and high pressure. The discharged refrigerant gas flows into the condenser.

[0047] The condenser condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment through the condensation process.

[0048] The throttling device causes the high-temperature, high-pressure liquid refrigerant condensed in the condenser to expand into a low-pressure liquid refrigerant.

[0049] The evaporator evaporates the refrigerant that expands in the throttling device and returns the refrigerant gas, now at a low temperature and low pressure, to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0050] In the case of an indoor heat exchanger and an outdoor heat exchanger, one of them is a condenser and the other is an indoor heat exchanger. When the indoor heat exchanger is used as a condenser, the air conditioner is used as a heater in heating mode. When the indoor heat exchanger is used as an evaporator, the air conditioner is used as a cooler in cooling mode.

[0051] To improve indoor air quality, in some embodiments of this application, the indoor unit of the air conditioner may include a fresh air module 10, which is disposed in the casing and used to introduce outdoor fresh air into the room. The fresh air module 10 and the indoor heat exchanger are spaced apart along the length of the casing.

[0052] Specifically, the casing may include a fresh air outlet, and the fresh air module 10 connects the outdoor environment to the fresh air outlet. The fresh air outlet provides a fresh air outlet path; outdoor fresh air, after being processed by the fresh air module 10, is smoothly discharged into the room through the fresh air outlet, realizing fresh air circulation. The fresh air outlet can be located at the bottom front of the indoor unit of the air conditioner, or on one side of the air conditioner's air outlet.

[0053] refer to Figure 1 The fresh air module 10 may include a fresh air fan 1, which is installed in the housing space to actively introduce outdoor fresh air. The fresh air fan 1 drives the fresh air flow, ensuring the efficient operation of the fresh air module 10.

[0054] refer to Figure 2 and Figure 4 The fresh air fan 1 may include a volute 11, which defines a fan cavity 15. The volute 11 has a volute inlet 13 connected to the fan cavity 15, and a volute outlet 14 connected to the fan cavity 15. The volute 11 provides an airflow channel, allowing airflow to move along the direction from the volute inlet 13 to the volute outlet 14.

[0055] In this embodiment, the volute inlet 13 serves as the inlet for external air to flow into the volute 11, allowing fresh outdoor air to enter the fan chamber 15 through the volute inlet 13. The volute outlet 14 serves as the outlet for fresh outdoor air to flow out of the volute 11, allowing airflow within the fan chamber 15 to flow out through the volute outlet 14. The volute outlet 14 is connected to the casing and communicates with the fresh air outlet, allowing the fresh outdoor air flowing out of the volute outlet 14 to reach the indoor environment.

[0056] In some embodiments of this application, the volute 11 can be formed by fastening together a first volute and a second volute, which is prior art and will not be described in detail here.

[0057] refer to Figure 5 The fresh air fan 1 can have a centrifugal impeller 12, which is located inside the fan chamber 15 and rotates in a first direction. The centrifugal impeller 12 is the core component of the fresh air fan 1. Its rotation generates centrifugal force to drive airflow, producing wind pressure and air volume.

[0058] The fresh air module 10 may include an air inlet shroud 2, which is connected to a volute 11, and the air inlet shroud 2 and the volute 11 together define an air inlet cavity 24. The air inlet cavity 24 is connected to the fan cavity 15 through the air inlet 13 of the volute. The air inlet cavity 24 serves as a transition area for fresh air flow from the outside to the centrifugal impeller 12. Proper design of the air inlet cavity 24 can improve the performance of the fresh air fan 1.

[0059] refer to Figures 2-4 The fresh air module 10 may include an air inlet duct 3, one end of which is connected to the air inlet cover 2, and the other end of which forms a fresh air inlet 31 that communicates with the air inlet cavity. The fresh air inlet 31 serves as the inlet for external air to flow into the fresh air module 10, allowing outdoor fresh air to enter the air inlet cavity 24 through the fresh air inlet 31.

[0060] refer to Figure 3 For example, in this embodiment, the air inlet shroud 2 and the volute 11 are connected to define an air inlet cavity 24 and a through portion 6 communicating with the air inlet cavity 24. The air inlet pipe 3 is installed at the through portion 6 and is connected to the air inlet shroud 2 and the volute 11 so that the fresh air inlet 31 communicates with the air inlet cavity 24 through the air inlet pipe 3.

[0061] The air inlet pipe 2 can be detachably connected to the air inlet cover 2 via the connecting structure 7, and the connecting structure 7 is integrated with the air inlet pipe 3.

[0062] Of course, in some other embodiments, the air inlet pipe 3 may only be connected to the air inlet cover 2, depending on the diameter of the fresh air inlet 31 and the thickness of the air inlet cavity 24.

[0063] In some embodiments, the fresh air inlet 31 can be connected to the outdoor environment through a fresh air corrugated duct. Under the rotation of the centrifugal impeller 12, outdoor fresh air enters the air intake chamber 24 through the fresh air inlet 31, and then enters the fan chamber 15 through the volute air inlet 13. After entering the fan chamber 15, the outdoor fresh air is accelerated by the centrifugal impeller 12, becoming high-pressure outdoor fresh air, and is then discharged through the volute air outlet 14, finally flowing into the room through the fresh air outlet.

[0064] In the fresh air module 10, refer to Figure 1 , Figure 4 A filter assembly 5 is installed inside the air inlet cavity 24 near the air inlet 13 of the volute. The filter assembly 5 includes a filter 51, which is used to filter outdoor fresh air to ensure the air quality delivered into the room. The filter 51 is installed in the air inlet cavity 15 via a filter bracket 52.

[0065] Given that the cross-sectional shape of the filter assembly 5 is typically approximately rectangular, the cross-section of the air inlet cavity 24 is also designed to be rectangular. In this system structure, the air inlet cavity 24 is the main source of resistance; under high airflow conditions, its resistance can account for 50% to 60% of the total resistance. Furthermore, after the outdoor fresh air enters the air inlet cavity 24, it will experience strong spiral motion due to the rotation of the centrifugal impeller 12. Excessive tangential velocity will lead to significant kinetic energy loss, which is detrimental to the full performance of the fan. Therefore, how to rationally organize the flow pattern within the air inlet cavity 24 to reduce flow resistance has become one of the key directions for improving the performance of the fresh air fan.

[0066] In related technologies, the common approach to optimizing the air resistance of the air inlet cavity 24 is to increase its thickness. However, this approach is limited by the overall assembly space. Another approach involves adding a guide structure 4 to the air inlet cavity 24. However, this neglects the rotation direction of the centrifugal impeller 12 and fails to properly organize the airflow, thus failing to simultaneously improve both air volume and efficiency.

[0067] In order to solve the above-mentioned technical problems, in this embodiment, the position and air inlet direction of the fresh air inlet 31 are reasonably set according to the rotation direction of the centrifugal impeller 12, the airflow is given a pre-swirl direction, and the pre-swirl direction of the airflow is opposite to the rotation direction of the centrifugal impeller 12.

[0068] Specifically, in this embodiment, the central axis P of the air inlet duct 3 forms an acute angle β with the ray OA pointing from the rotation center O of the centrifugal impeller 12 to the geometric center A of the fresh air inlet 31. (Refer to...) Figure 6 The central axis P is deflected in the opposite direction to the first direction relative to the ray OA. In other words, the opening direction of the acute angle β is away from the first direction.

[0069] This acute-angle design ensures that the fresh airflow entering the inlet chamber 24 is not radially aligned with the center of the centrifugal impeller 12, but rather possesses a tangential velocity component. The opening direction of the acute angle β is opposite to the rotation direction of the centrifugal impeller 12, which makes the initial tangential velocity direction of the fresh airflow opposite to the rotation direction of the centrifugal impeller 12. This "reverse pre-rotation" increases the relative velocity difference between the fresh airflow and the rotating centrifugal impeller 12, allowing the impeller to more effectively transfer energy to the fresh airflow, enhancing the work capacity of the fresh air fan, and ultimately improving air volume and efficiency.

[0070] In some embodiments of this application, reference is made to Figures 7-11The fresh air module 10 may include a flow guiding structure 4, which is disposed on the side wall of the air inlet shroud 2 away from the centrifugal impeller 12, to guide the airflow entering through the fresh air inlet 31 to form a pre-swirling airflow. The rotation direction of the pre-swirling airflow is opposite to the first direction.

[0071] The flow guide structure 4 strengthens and shapes the pre-swirl trend generated by the aforementioned angle design, ensuring a stable and uniformly oriented pre-swirl airflow. This further enhances the pre-swirl effect and ensures that the pre-swirl direction is opposite to the rotation direction of the centrifugal impeller 12. The flow guide structure 4 effectively organizes the airflow motion, reduces dead zones and vortices, and lowers the resistance of the inlet chamber 24.

[0072] refer to Figure 7 , Figure 8 The airflow guiding structure 4 may include two airflow guiding vanes, which are arranged sequentially along the axial direction of the fresh air inlet 31.

[0073] A two-stage flow guiding structure 4, consisting of two guide vanes, allows for phased airflow control. The first-stage guide vane initially guides the airflow, while the second-stage guide vane further optimizes the flow. The two guide vanes forcefully guide the airflow, transforming it from disordered, large-scale circular motion into a more ordered motion along the vane profile, pointing towards the axis of the centrifugal impeller 12. This reduces circumferential momentum loss, and the tangential velocity of the airflow is limited and reduced by the guide vanes, thereby increasing the axial velocity. This two-stage flow guiding improves flow field uniformity, reduces the pressure gradient, and thus significantly reduces wind resistance, improving the performance of the fresh air fan.

[0074] Further reference Figure 7 A flow channel 43 is formed between the two flow guides, and the flow channel 43 shows a trend of first contraction and then expansion from upstream to downstream.

[0075] The contraction-expansion design of the guide channel 43 accelerates the airflow in the contraction section, effectively enhancing its overall kinetic energy and particularly its axial velocity component. Guided by the profile of the guide vanes, the accelerated airflow adheres more closely to the surface of the guide vanes, thus suppressing flow separation. After acceleration, the airflow enters the expansion section, where the flow cross-sectional area increases, allowing the velocity to decrease gradually, i.e., the pressure to recover. This gradual deceleration effectively reduces energy loss and greatly helps maintain airflow stability, preventing the formation of new vortices due to drastic velocity changes.

[0076] In this embodiment, by setting a guide channel that contracts first and then expands, the pressure gradient in the air inlet cavity 24 is effectively reduced, so that the airflow can enter the fan more smoothly and evenly, ultimately achieving the purpose of reducing flow resistance and circumferential momentum loss and improving the fan's work capacity.

[0077] It should be noted that when the fresh airflow enters the air inlet cavity 24, it is basically perpendicular to the side wall opposite the fresh air inlet 31, and is a radial airflow; while the axial airflow is parallel to the side wall opposite the fresh air inlet 31, which facilitates the flow into the volute 11.

[0078] Understandably, after the fresh airflow enters the air inlet cavity 24 from the fresh air inlet 31, it flows towards the side wall opposite to the fresh air inlet 31 and along that side wall toward the volute air inlet 13, thus leaving the air inlet cavity 24 and entering the fan cavity 15. The guide vanes make it easier for the airflow to enter the fan cavity 15.

[0079] Define the air guide vane closer to the fresh air inlet 31 as the first air guide vane 41, and the other air guide vane as the second air guide vane 42. (Reference) Figure 8 The tangent at the upstream end of the profile of the first guide vane 41 is parallel to the central axis P of the fresh air inlet 31.

[0080] The tangent at the upstream end of the profile of the first guide vane 41 is parallel to the central axis P of the fresh air inlet 31, so that the fresh air flow does not have a significant angle of attack when it comes into contact with the first guide vane 41. This allows for seamless connection and smooth transition of the fresh air flow, fundamentally avoiding eddies and turbulence caused by impacting the leading edge of the guide vane, and greatly reducing the impact loss at the fresh air inlet 31.

[0081] In this embodiment, the airflow entering through the fresh air inlet 31 passes through two stages of guide vanes, which effectively reduces the circumferential momentum loss of the airflow, increases the axial velocity, and reduces the flow resistance and kinetic energy loss of the air inlet cavity 24, thereby improving the fan's air volume and efficiency. This effectively solves the problem of high resistance in the air inlet cavity 24 and excessive tangential velocity of the airflow leading to kinetic energy loss in the prior art.

[0082] Preferably, the tangent at the upstream end of the profile of the first guide vane 41 coincides with the central axis P of the fresh air inlet 31. This arrangement enables "zero-impact air intake" and minimizes energy loss at the fresh air inlet 31.

[0083] In some embodiments of this application, the first guide vane 41 is arc-shaped, the diameter of the fresh air inlet 31 is d, and the radius r1 of the arc of the first guide vane 41 satisfies: r1≥1.5d, r1≤2d. Wherein, r is the inner diameter of the fresh air inlet 31.

[0084] If the radius of the arc r1 is less than 1.5d, it will result in excessive curvature, causing a drastic change in airflow direction, which can easily lead to significant impact losses and flow separation.

[0085] If the radius of the arc r1 is greater than 2d, the curvature will be too small, the airflow velocity in the circumferential direction will not decrease significantly, which is not conducive to increasing the axial velocity of the airflow. The airflow flow will be severely lost, which is not conducive to achieving the purpose of drag reduction.

[0086] In this embodiment, the first guide vane 41 adopts an arc-shaped design, and the arc radius r1 is in the range of 1.5d to 2d, which can optimize the airflow direction, reduce local eddies and separation, and make the airflow smoothly transition to the second-stage guide vane, resulting in a significant drag reduction effect.

[0087] In some embodiments of this application, the central angle a1 corresponding to the first guide vane 41 satisfies: a1≥55°, a1≤70°.

[0088] A central angle a1 greater than 70° will cause excessive airflow reversal, increasing friction loss and reducing fan efficiency.

[0089] If the central angle a1 is less than 55°, the turning is insufficient, the airflow cannot be effectively pre-swirled, and the drag reduction effect is reduced.

[0090] In this embodiment, by setting the central angle a1 within the range of 55° to 70°, the airflow is effectively pre-swirled and redirected, reducing energy loss.

[0091] In some embodiments of this application, the distance t between the first guide vane 41 and the end of the air inlet pipe 3 furthest from the fresh air inlet 31 satisfies: t≥0.25d, t≤0.35d.

[0092] When the spacing t > 0.35d, the airflow may diffuse prematurely, leading to energy loss and flow field instability. When the spacing t < 0.25d, the airflow is compressed, increasing impact losses and potentially inducing eddies.

[0093] In this embodiment, by setting the spacing t in the range of 0.25d to 0.35d, the airflow impact loss is reduced, ensuring that the airflow enters the guide structure 4 smoothly and avoiding energy loss caused by compression or diffusion when the airflow enters the guide structure 4.

[0094] In some embodiments of this application, the second guide vane 42 is arc-shaped, and the radius r2 of the arc of the second guide vane 42 satisfies: r2≥1.5d, r2≤2d. Wherein, d is the diameter of the fresh air inlet 31.

[0095] If the radius of the arc r2 > 2d, the airflow guidance is insufficient, the reduction in circumferential momentum is not obvious, and the drag reduction effect is poor.

[0096] If the radius of the arc r2 < 1.5d, the airflow will turn too sharply, increasing flow separation and energy loss.

[0097] In this embodiment, by setting the radius r2 of the arc in the range of 1.5d to 2d, it cooperates with the first guide vane 41 to form an effective secondary guide, ensuring that the airflow smoothly turns on the second guide vane 42, further reducing the circumferential momentum loss, increasing the axial velocity of the airflow, and improving the performance of the fresh air fan 1.

[0098] In some embodiments of this application, the central angle a2 corresponding to the second guide vane 42 satisfies: a2≥90°, a2≤120°.

[0099] If the central angle a2 exceeds 120°, it may cause excessive airflow deflection, increasing friction loss and drag.

[0100] If the central angle a2 < 90°, the curvature of the second guide vane 42 is small, and its guiding effect on the airflow is weak. It cannot form an ideal reverse pre-swirling flow field, and the circumferential velocity of the airflow is still high, which limits the increase of the axial velocity.

[0101] In this embodiment, by setting the central angle a2 of the second guide vane 42 within the range of 90°~120°, the airflow is ensured to turn fully, the axial velocity is increased, the circumferential momentum is reduced, and the work capacity of the fresh air fan 1 is improved.

[0102] Along the direction of the fresh air flow, the guide vanes have upstream and downstream ends. (Reference) Figure 9 The air inlet shroud 2 has a second sidewall 22 adjacent to the fresh air inlet 31. The upstream end of the second guide vane 42 is closer to the second sidewall 22 than the downstream end.

[0103] Continue to refer to Figure 9 The distance L1 between the upstream end of the second guide vane 42 and the second sidewall 22 satisfies: L1≥0.5d, L1≤0.55d.

[0104] The air inlet hood 2 has a third sidewall 23 opposite to the fresh air inlet 31. The distance L2 between the upstream end of the second guide vane 42 and the third sidewall 23 satisfies: L2≥0.97d, L1≤1.1d.

[0105] If L1 < 0.5d or L2 < 0.97d, the second guide vane 42 is too close to the side wall of the air inlet shroud 2, causing flow blockage or dead zone and increasing resistance.

[0106] If L1>0.55d or L2>1.1d, the second guide vane 42 may be too close to the center of the air inlet cavity 24, resulting in insufficient airflow guidance and insignificant reduction in circumferential momentum.

[0107] In this embodiment, by setting the distance L1 in the range of 0.5d to 0.55d and setting the distance L2 in the range of 0.97d to L1≤1.1d, the position of the second guide vane 42 in the air inlet cavity 24 is optimized, avoiding interference with the wall of the air inlet shroud 2, guiding the airflow to be evenly distributed, reducing the pressure gradient in the air cavity, and improving the uniformity of the flow field.

[0108] In some embodiments of this application, reference continues to be made to Figure 9 The minimum distance Lmin between the first guide vane 41 and the second guide vane 42 satisfies: Lmin≥1d, Lmin≤1.2d.

[0109] If the minimum distance Lmin > 1.2d, the flow channel is too loose, the airflow cannot be effectively accelerated, and the drag reduction effect is poor.

[0110] If the minimum distance Lmin < 1d, the contraction point of the guide channel is too narrow, increasing flow resistance and impact loss.

[0111] In this embodiment, by setting the minimum distance Lmin within the range of 1d to 1.2d, the cross-section of the guide channel is controlled to first contract and then expand, optimizing the acceleration and deceleration of the airflow, reducing energy loss, and helping to achieve the purpose of drag reduction.

[0112] It should be noted that, in this embodiment, the minimum distance between the first guide vane 41 and the second guide vane 42 is the distance between the downstream end of the first guide vane 41 and the second guide vane 42.

[0113] In some embodiments of this application, one end of the guide vane is connected to the side wall of the air inlet shroud 2, and the other end extends along the axial direction of the centrifugal impeller 12 towards the centrifugal impeller 12 to form a free end.

[0114] refer to Figure 11 The height h of the guide vane in the axial direction of the centrifugal impeller 12 satisfies: h ≥ 0.45H, h ≤ 0.52H. Wherein, H is the thickness of the air inlet cavity 24 in the axial direction of the centrifugal impeller 12.

[0115] If the height h of the guide vane is greater than 0.52H, it is more likely to interfere with the filter screen installed at the air inlet 13 of the volute, affecting the installation and use of the filter screen.

[0116] If the height h of the guide vane is less than 0.45H, it cannot effectively interfere with the main airflow, and the airflow reorganization is not obvious.

[0117] In this embodiment, by setting the height h of the guide vane in the range of 0.45H to 0.52H, and relating it to the thickness of the air inlet cavity 24, it is ensured that the guide vane can effectively interfere with and guide the main airflow, reorganize the airflow, and at the same time avoid interference with the filter.

[0118] In some embodiments of this application, reference continues to be made to Figure 11 The guide vanes are set to be of equal thickness, and the thickness m of the guide vanes satisfies: m≥2mm, m≤3mm.

[0119] If the thickness m of the guide vane is greater than 3mm, the drag reduction effect will not be improved; instead, it will increase the weight and cost of the air intake shroud 2.

[0120] If the thickness m of the guide plate is less than 2mm, the strength of the guide plate is insufficient, and it may deform or be damaged after long-term use, affecting its service life.

[0121] In this embodiment, by setting the thickness m in the range of 2mm to 3mm, the structural strength and drag reduction effect of the guide vane are effectively balanced, thus solving the strength problem or ineffective weight increase problem caused by improper thickness of the guide vane.

[0122] In some embodiments of this application, the two guide vanes have the same height h in the axial direction of the centrifugal impeller 12. Two guide vanes with the same height h can reliably avoid interference with the downstream filter screen.

[0123] Specifically, when the two guide vanes have the same height h, the minimum gap between them and the downstream filter screen is uniform. Production only needs to ensure that one height value h meets the safety gap requirement, simplifying manufacturing and assembly and reducing costs. At the same time, the flow channel formed by the two guide vanes of the same height has a uniform cross-section in the axial direction of the centrifugal impeller 12, ensuring that the airflow receives the same guiding effect at every position in the axial direction. This provides a stable and consistent axial flow space for the airflow, ensuring the uniformity of the flow field.

[0124] To verify the technical effectiveness of this solution, computational fluid dynamics (CFD) simulations were performed on the inlet cavity before optimization (reference) and the optimized inlet cavity 24, which incorporates the secondary flow guiding structure 4 of this application and adjusts the position of the fresh air inlet 31. The results are as follows: Figures 13 to 15 As shown.

[0125] Figure 13 The image shows a comparison of the circumferential velocity of the airflow within the inlet cavity 24 before and after optimization. (Example:) Figure 13 As shown in Figure a, a large region of high circumferential velocity exists within the reference inlet cavity 24 (primarily marked in red), indicating disordered airflow rotation within the cavity, resulting in significant circumferential momentum loss and eddy current losses. In contrast, in Figure 13 As shown in b, in the optimized air inlet cavity 24 of this application, the range and intensity of the high circumferential velocity region are significantly reduced, and the airflow is effectively 'smoothed', proving that the secondary guide structure 4 successfully suppresses ineffective tangential flow.

[0126] Figure 14The image shows a comparison of the axial velocity of the airflow within the inlet cavity 24 before and after optimization. Figure 14 As can be seen from point a, the axial velocity distribution of the reference air inlet 24 is uneven and generally low (mainly blue), indicating insufficient airflow delivery capacity towards the centrifugal impeller. Figure 14 The scheme of this application shows that the axial velocity of the core flow region of the air inlet cavity 24 is significantly and uniformly improved (a larger area of ​​yellow or red is visible), which directly confirms that the secondary flow guide structure 4 converts more of the air kinetic energy into effective axial motion, thereby improving the airflow delivery efficiency.

[0127] Figure 15 The image shows a comparison of the static pressure distribution across the cross-section of the air inlet 24 before and after optimization. Figure 15 In the reference inlet cavity 24 of component a, the static pressure distribution is extremely uneven, with a severe pressure gradient (represented by the red dashed box), which directly reflects high flow resistance and energy loss. Conversely... Figure 15 In the optimized inlet cavity 24 of b, the static pressure distribution becomes more continuous and gentle, and the color of the entire area tends to be uniform. This indicates that by optimizing the flow, this application significantly reduces the pressure gradient and flow loss within the inlet cavity 24, thereby improving the flow field uniformity. In summary, the indoor air conditioning unit proposed in this invention employs a two-stage airflow guiding structure 4 in its fresh air module, which significantly reduces the tangential velocity of the airflow within the air inlet cavity 24 and increases the axial velocity of the airflow. This helps to reduce the pressure gradient within the air inlet cavity 24 and improve the uniformity of the flow field. Compared with a reference fresh air module having a reference air inlet cavity 24, the optimized fresh air fan 1 increases the air volume by 8.4% and the efficiency by 6.9%.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0129] For ease of explanation, the above description has been provided in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. Various modifications and variations can be obtained based on the above teachings. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, thereby enabling those skilled in the art to better utilize the described embodiments and various different variations of embodiments suitable for specific use considerations.

Claims

1. An indoor unit for an air conditioner, characterized in that, include: A housing having an internally defined receiving space, the housing including a fresh air outlet; A fresh air fan, installed in the accommodating space, is used to introduce fresh outdoor air. The fresh air fan includes: A volute, which defines a fan cavity inside, is provided with a volute air inlet and a volute air outlet communicating with the fan cavity, and the volute air outlet is connected to the fresh air outlet. A centrifugal impeller is disposed inside the fan cavity, and the centrifugal impeller rotates in a first direction; An air inlet shroud, connected to the volute, together defines an air inlet cavity, which is connected to the fan cavity through the air inlet of the volute. An air inlet duct, one end of which is connected to the air inlet hood, and the other end of which forms a fresh air inlet communicating with the air inlet cavity; A flow guiding structure is provided on the side wall of the air inlet shroud away from the centrifugal impeller to guide the airflow entering the fresh air inlet to form a pre-swirling airflow, the rotation direction of the pre-swirling airflow being opposite to the first direction; The airflow guiding structure includes two airflow guiding vanes arranged sequentially along the axial direction of the fresh air inlet, and an airflow guiding channel is formed between the two airflow guiding vanes. The airflow guiding channel has a tendency to first contract and then expand from upstream to downstream. The guide vane closer to the fresh air inlet is defined as the first guide vane, and the other guide vane is defined as the second guide vane. The tangent at the upstream end of the profile of the first guide vane is parallel to the central axis of the air inlet duct.

2. The indoor unit of the air conditioner according to claim 1, characterized in that, The first guide vane is arc-shaped, the diameter of the fresh air inlet is d, and the radius r1 of the arc of the first guide vane satisfies: r1≥1.5d, r1≤2d.

3. The indoor unit of the air conditioner according to claim 1 or 2, characterized in that, The central angle a1 corresponding to the first guide vane satisfies: a1≥55°, a1≤70°.

4. The indoor unit of the air conditioner according to claim 2, characterized in that, The distance t between the first guide vane and the end of the air inlet pipe furthest from the fresh air inlet satisfies: t≥0.25d, t≤0.35d.

5. The indoor unit of the air conditioner according to claim 1, characterized in that, The second guide vane is arc-shaped, the diameter of the fresh air inlet is d, and the radius r2 of the arc of the second guide vane satisfies: r2≥1.5d, r2≤2d.

6. The indoor unit of the air conditioner according to claim 1 or 5, characterized in that, The central angle a2 corresponding to the second guide vane satisfies: a2≥90°, a2≤120°.

7. The indoor unit of the air conditioner according to claim 1, characterized in that, The air inlet hood has a second sidewall adjacent to the fresh air inlet and a third sidewall opposite to the fresh air inlet, and the diameter of the fresh air inlet is d; The distance L1 between the upstream end of the second guide vane and the second sidewall satisfies: L1≥0.5d, L1≤0.55d; and / or, the distance L2 between the upstream end of the second guide vane and the third sidewall satisfies: L2≥0.97d, L1≤1.1d.

8. The indoor unit of the air conditioner according to claim 2 or 5, characterized in that, The minimum distance Lmin between the first guide vane and the second guide vane satisfies: Lmin≥1d, Lmin≤1.2d.

9. The indoor unit of the air conditioner according to claim 1, characterized in that, One end of the guide vane is connected to the side wall of the air inlet shroud, and the other end extends towards the centrifugal impeller to form a free end. The two guide vanes have the same height h in the axial direction of the centrifugal impeller, and h satisfies: h≥0.45H, h≤0.52H; H is the thickness of the air inlet cavity in the axial direction of the centrifugal impeller.

10. The indoor unit of the air conditioner according to claim 1, characterized in that, The guide vanes are of uniform thickness, and the thickness m of the guide vanes satisfies: m≥2mm, m≤3mm; and / or, the central axis of the air inlet duct forms an acute angle with the ray pointing from the rotation center of the centrifugal impeller to the geometric center of the fresh air inlet, and the central axis is deflected in the opposite direction to the first direction relative to the ray.

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